Oxalyl chloride → HCID 86665169, compound

Participants

Reaction Steps

According to Scheme 2, Step 2: To a solution of 1-(4-methoxybenzyl)-3-methyl-1H-pyrazole-4-carboxylic acid (37.8 mmol, 9.30 g) and five drops of DMF in DCM (94 mL) was added oxalyl chloride (76 mmol, 6.66 mL) dropwise, at 0° C. The reaction mixture was allowed to warm up to room temperature and was stirred for 3 hours. After concentration, the residue was treated with toluene and was co-evaporated to dryness to yield 1-(4-methoxybenzyl)-3-methyl-1H-pyrazole-4-carbonyl chloride. To a solution of 1-(4-methoxybenzyl)-3-methyl-1H-pyrazole-4-carbonyl chloride (37.8 mmol) in acetonitrile (94 mL) was added a solution of TMSCHN2 (41.5 mmol, 83.0 mL) dropwise, at 0° C., and then the reaction mixture was allowed to warm up to room temperature and was stirred overnight. After cooling the reaction mixture to −10° C., HBr 48% (14.8 mL) was added dropwise and the reaction mixture was stirred for 2 hours at −10° C. At 0° C., 10% NaOH solution was added to the reaction mixture to reach pH=7. The reaction mixture was diluted with water and EtOAc and the aqueous phase was extracted with EtOAc. The organic phase was dried over MgSO4, was filtered and was concentrated under reduced pressure to yield 2-bromo-1-(1-(4-methoxybenzyl)-3-methyl-1H-pyrazol-4-yl)ethanone (30.6 mmol, 9.90 g, 81%) which was used without any purification.

Provenance & Evidence